In a known manner, the escapement of a mechanical timepiece movement, whether it be a Swiss or coaxial lever escapement, comprises a more or less complex assortment of parts, including an escape wheel whose regularly spaced teeth absorb the shock of the pallet stones, generally made of ruby. The shape of this wheel, shown in FIG. 2, has practically never changed. It comprises a central rigid zone 2, provided with an aperture 4 for driving onto an arbour; a rigid felloe 12 provided with teeth 8, and generally four arms 6, which are also rigid, which form a rigid part. Improvements have related to the number or shape of the teeth in particular for facilitating lubrication and reducing wear. Swiss Patent No. CH 230 743 and German Patent No. DE 1 192 984 disclose for example embodiments wherein the teeth comprise notches for forming oil reservoirs.
In order to have sufficient mechanical resistance, the material used for manufacturing such escape wheels is practically always a metal or alloy. This does not however totally exclude the risk of the teeth being damaged in the event of too violent shocks. This risk is further increased if a more shock sensitive material replaces the metal.